Thermoformed Polyester Closures for PET Recycling Compatibility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional container closures made from HDPE and PP are not recyclable with PET containers, leading to contamination and inefficiencies in recycling streams due to incompatibility, and injection molding limits the thinness of these closures.
Innovation Solution
Developing closures from thermoformed polyester resin, particularly polyethylene furandicarboxylate (PEF), which can be recycled with PET containers and features an interference fit for sealing, allowing for lighter and more efficient manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional injection molding is used to manufacture closures from HDPE or PP, then the closures can be produced with sufficient structural integrity, but the closures become incompatible with PET recycling streams and cause contamination
Solution Approach 1:
The closure is made from the same polyester resin material as the container body, creating material homogeneity that enables compatible recycling. This eliminates the need to separate closures from containers during recycling, preventing contamination of PET recycling streams while maintaining structural integrity through the polyester material properties
2Productivity
If injection molding is used to manufacture closures, then closures can be produced efficiently, but the wall thickness cannot be reduced below certain limits due to flow rate restrictions and ejection difficulties
Solution Approach 1:
The patent replaces the injection molding process with a thermoforming process. Thermoforming allows for the creation of thin-walled closures by heating and forming polyester resin sheets over molds, eliminating the flow rate restrictions and ejection difficulties inherent in injection molding. This enables production of lighter-weight closures with wall thicknesses optimized for minimal material usage while maintaining structural integrity
3Reliability
If HDPE or PP materials are used for closures, then the closures can be manufactured with adequate sealing properties, but they create incompatibility issues in automated recycling sorting
Solution Approach 1:
By making the closure from the same polyester resin as the container, the invention creates material homogeneity that ensures both sealing performance and recycling compatibility. The polyester material provides adequate sealing properties while being readily identifiable and recyclable in automated sorting systems, eliminating the incompatibility issues caused by HDPE or PP materials
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The polyester resin closures provide improved recyclability, reduce contamination, enhance oxygen and carbon dioxide barriers, and ensure effective sealing without deformation, while being compatible with PET containers for better recycling and shelf-life enhancement.
Implementation Method 1
an inner cylindrical wall that extends downwardly from the annular wall, the inner cylindrical wall configured such that an outwardly facing surface of the inner cylindrical wall has an interference fit with an inwardly facing surface of the finish of the container for sealing against the inwardly facing surface of the finish
Implementation Method 2
enhance oxygen and carbon dioxide barriers
Data Source
AI summary
Thermoformed polyester resin closures for closing containers, the polyester resins including polyethylene terephthalate (“PET”), polyethylene furandicarboxylate (“PEF”), or a copolymer including PET and PEF, are provided herein. Methods of making the thermoformed closures are further provided. Methods of sterilizing the thermoformed closures are further provided.